1. Field of the Invention
The present invention relates to a medical imaging diagnosis apparatus preferable for early detection of the cancer or the like, particularly relates to a medical imaging diagnosis apparatus capable of taking both of a PET (positron emission tomography) image and an X-ray CT image.
2. Description of the Related Art
PET examination obtains a distributed image (tomographic image) of a positron emitting nuclide at a specific section of a subject person by calculation. After labeling a drug having a property of gathering to the focus of the cancer by a positron emitting nuclide, the drug is administered into the human body. In positron annihilation, gamma rays are emitted in directions opposed to each other by 180° and therefore, the gamma rays are detected at 360° surrounding of the human body to catch simultaneous incidence of the two gamma rays. Since the nuclide is disposed on a line connecting positions of the incidence, data of the line connecting the positions of incidence is provided as position data. The distributed image of the nuclide is reconstructed by collecting the position data for a constant period of time to subject to operational processing. The distributed image (tomographic image) represents a size and a shape of the cancer focus per se and therefore, direct diagnosis can be carried out. However, since the PET image only represent a state of accumulating and distributing the nuclide, it is not necessarily clear at what location of the human tissue the nuclide is present.
Meanwhile, according to an X-ray CT apparatus, by rotating an X-ray tube and an X-ray detector at a surrounding of the body axis of the subject person, X-ray projection data (absorption distribution data) from respective directions in a section orthogonal to the body axis are collected. Then, by subjecting the projection data to back projection, an image (X-ray CT image) of an X-ray absorption rate distribution at the section is reconstructed. The X-ray CT image represents the shape of the tissue at inside of the human body at the section.
Hence, in order to carry out ensured diagnosis, it is effective to use both of the PET image and the X-ray CT image. In a related art, there has been conceived a medical imaging diagnosis apparatus placing a PET apparatus and an X-ray CT apparatus in parallel relative to a single common examination couch, or integrally constituting the PET apparatus and the X-ray CT apparatus to be able to take a PET image and a CT image for the same subject person.
However, even in the case of placing the PET apparatus and the X-ray CT apparatus in parallel or even in the case of integrally constituting the PET apparatus and the X-ray CT apparatus, the subject person is inserted into tunnel portions of cabinets referred to as gantries of the both apparatus. Therefore, blocked feeling or oppressed feeling of the subject person poses a problem.
Further, JP-A-7-20245 describes a system of using a PET apparatus and an X-ray CT apparatus and an examination couch common thereto. However, according to the system, data provided by the X-ray CT apparatus is intended to use for correction of absorption of PET data and the system does not intend to provide a CT image for diagnosis from the X-ray CT apparatus. Further, nothing is conceived for improving blocked feeling or oppressed feeling which the subject person undergoes when the subject person passes tunnel portions of both of the PET apparatus and the X-ray CT apparatus.
Further, JP-A-11-164829 shows an X-ray CT apparatus for carrying out helical scan while continuously moving a gantry of the X-ray CT apparatus relative to a subject person fixed onto an examination couch, and there is not a description with regard to blocked feeling or oppressed feeling which the subject person undergoes.